UPnP UUID's seem to be one character short
The UPnP seems to give UUID's that are not 128 bit.
This seems to have also happned to this person: https://github.com/syncthing/syncthing/issues/890
It for example reports "3c31ff43-e200-033c-a66f-e719d083f3f" as the UUID. The last group misses one character (one 4-bit portion) as it should be 8-4-4-4-12.
I'm wondering is that a configuration mistake? The GUI does not seem to offer much in the sense of UUID type/version and the like.